Conventional micro-fluid ejection heads are designed and constructed with silicon micro-fluid ejection head chips that include both the ejection actuators for ejection of fluids and logic circuits to control the ejection actuators. However, the silicon wafers used to make silicon chips are currently only available in round format because the basic manufacturing process is based on a single seed crystal that is rotated in a high temp crucible to produce a circular boule that is processed into thin circular wafers for the semiconductor industry.
The circular wafer stock is very efficient for relatively small micro-fluid ejection head chips relative to the diameter of the wafer. However, such circular wafer stock is inherently inefficient for use in making large rectangular silicon chips such as chips having a dimension of 2.5 centimeters or greater. In fact the expected yield of silicon chips having a dimension of greater than 2.5 centimeters from a circular wafer is typically less than about 20 chips. Such a low chip yield per wafer makes the cost per chip prohibitively expensive.
Accordingly, there is a need for improved structures and methods for making micro-fluid ejection heads, particularly ejection heads suitable for ejection devices having an ejection swath dimension of greater than about 2.5 centimeters.
In view of the foregoing and/or other needs, exemplary embodiments of the disclosure provide a micro-fluid ejection head including a non-conventional substrate and methods for making large array micro-fluid ejection heads. One exemplary micro-fluid ejection head includes a substrate having a plurality of fluid ejection actuator devices adjacent to a device surface thereof. A valley is adjacent to the device surface. A semiconductor chip associated with the plurality of fluid ejection actuator devices is in the valley adjacent the device surface of the substrate. A conductive material is deposited adjacent to the device surface of the substrate, wherein the deposited conductor material generally conforms to the valley. The conductor material is in electrical flow communication with the chip.
Another exemplary embodiment of the disclosure provides a method for fabricating a micro-fluid ejection head. A conductive material is deposited into a valley of a substrate. The valley is adjacent to a device surface of the substrate. A semiconductor chip is provided in the valley such that the chip is in electrical flow communication with fluid ejection actuators formed adjacent the device surface. The valley is substantially filled with an encapsulant material to substantially planarize the device surface. A nozzle plate is provided adjacent to the device surface of the substrate.
A potential advantage of an exemplary apparatus and method described herein is that large array substrates may be fabricated from non-conventional substrate materials including, but not limited to, glass ceramic, metal, and plastic materials. The term “large array” as used herein means that the substrate is a unitary substrate having a dimension in one direction of greater than about 2.5 centimeters. However, the apparatus and methods described herein may also be used for conventional size ejection head substrates.
Another potential advantage of an exemplary embodiment of the disclosure is an ability to dramatically reduce the amount of semiconductor device area required to drive a plurality of fluid ejection actuators.